Color vision deficiency screening test resistant to display calibration errors

ABSTRACT

A method for testing a plurality of regions in a color space to identify any of, or a subcombination of, the following color vision deficiencies: protanopia, deuteranopia, tritanopia, and related anomalies. A set of distractor colors is distributed across a region of color space such that the confusion line through a single target color intersects approximately the middle of the set. The distractor set spans a region extending in both chromaticity and luminance, which provides leeway for display errors since the confusion line will intersect the set even if colors do not render exactly as specified, and color deficient observers would still not be able to identify the target. A web-based implementation enables remote testing of subjects.

CROSS-REFERENCE TO OTHER APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 10/277,712 filed on Oct. 22, 2002 which claimspriority to U.S. provisional patent application Ser. No. 60/338,950,filed on Oct. 22, 2001.

BACKGROUND OF THE INVENTION

The invention relates to the field of vision testing and, in particular,to a color vision deficiency test using a computer display.

For a number of testing situations, such as remote testing over theInternet, the main challenge is to develop a color vision deficiencytest that can provide meaningful assessment in spite of the degradationsinherent in uncalibrated and otherwise unknown display devices. Often,performance on psychophysical tests can improve when devicemiscalibrations lead to artifacts that provide additional cues for thecorrect target, resulting in a higher false negative rate for detectingsensory deficiencies, meaning that color deficient observers areinappropriately categorized as not having color vision deficiencies. Bydesigning the presentation so that limitations in the display increasethe false alarm rate (instead of the false negative rate), a moreconservative measure of performance is achieved. The benefit for ascreening evaluation is that it is less likely that a person having asensory deficit will be overlooked, i.e., more people in need ofattention will be directed to the appropriate clinicians.

Colors can be described by coordinates in a three-dimensional colorspace; an example of this is the RGB triplet used to specify colors on acomputer monitor. Color vision deficiencies can be characterized byconfusion lines in a color space, wherein two colors lying on such aline are difficult or impossible to discriminate from each other by acolor deficient observer. Many tests of color vision exploit thisphenomenon, and their reliability hinge on the precision with which testcolors can be specified. However, if one has only limited control ofmonitor calibration, as is the case when testing over the Internet,colors displayed at a remote location generally do not render asspecified. Color deficient observers could thus pass the test if colorsdo not fall on a confusion line, which is a disastrous failure mode andone of the main reasons color vision assessment is not generallyfeasible outside a carefully controlled clinical setting.

There are three major types of color vision deficiencies: protanopia,deuteranopia, and tritanopia, corresponding to an absence ormalfunctioning of long, medium, and short wavelength-sensitive conephotoreceptors, respectively. Subcategories of color vision deficiencyare the “anomalous” versions of each of the three major categories. Thethree major categories are characterized by the inability todiscriminate colors along particular confusion lines in color space.Anomalies are characterized by greater difficulty, as compared to colornormal observers, in discriminating colors along similar confusion linesas the corresponding major deficiencies. Each major type of color visiondeficiency requires a test series tailored to its unique set ofconfusion lines. Each major type of color vision deficiency requires atest series.

SUMMARY OF THE INVENTION

The present invention provides for a method for testing in a pluralityof regions in a color space to identify any of, or a subcombination of,the following color vision deficiencies: protanopia, deuteranopia, andtritanopia, as well as related anomalies. In the methodology embodied inthe color vision test of the present invention, a set of distractorcolors is distributed across a region of color space such that theconfusion line through a single target color intersects approximatelythe middle of the distractor set. The distractor set spans a regionextending in both chromaticity and luminance, which provides leeway fordisplay errors since the confusion line will intersect the set even ifcolors do not render exactly as specified, and color deficient observerswould still not be able to identify the target. This provides protectionagainst the most disastrous failure mode.

In an exemplary embodiment, the step of identifying a threshold is basedupon a staircase method to adaptively increase the color separationuntil the subject is able to consistently identify said target color anddecrease the color separation until the subject is not able toconsistently identify the target color, wherein the threshold isidentified based on the upper and lower reversal points of thestaircase.

Additionally, in another embodiment, the present invention provides fora web-based color deficiency vision test implemented over a network andrendered on computer displays associated with test subjects.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 a illustrates the pattern of chromatic shift for gamma=1.2(undercorrected).

FIG. 1 b illustrates the pattern of chromatic shift for gamma=0.8(overcorrected).

FIG. 2 illustrates the pattern of a red shift.

FIG. 3 a illustrates the present invention methodology for selection ofcolors within a color space.

FIG. 3 b illustrates a close-up, top-down view of the equiluminant planeshown in FIG. 3 a.

FIG. 4 illustrates an example showing the appearance of the test plate.

FIGS. 5 a-c collectively illustrate the present invention's methodologyfor testing within several regions of the color space.

FIG. 6 illustrates an exemplary embodiment associated with the presentinvention's method for testing a plurality of regions in a color spaceto identify color vision deficiencies.

FIG. 7 illustrates a method outlining an exemplary application of thepresent invention.

FIG. 8 illustrates a system implementing the present invention's visiontesting method via a stand-alone vision testing server or a visiontesting server working in conjunction with an Internet Service Provider(ISP).

DETAILED DESCRIPTION OF THE INVENTION

There are a number of ways in which colors displayed on a cathode raytube (CRT) are likely to deviate from their desired values. Colors shiftin ways characteristic of the physical properties of CRT displays, andit is the systematic nature of these color errors that permitincorporation of safeguards in the color screening test proposed here.To our knowledge, no currently available color test explicitly addressesthese possible sources of false positive, or worse, false negative,diagnoses. A brief outline regarding some of the most important factorsaffecting color rendition is now provided.

CRT monitors exhibit characteristic color shifts in the colors theydisplay when they are not calibrated correctly. However, since for agiven monitor the chromaticities of the primary colors do not varysignificantly with the calibration state, all color shifts must occurwithin the region of the color space delimited by the primarychromaticities. Thus, if sets of colors within one region of the colorspace are expanded due to display miscalibration, with the colorscontained in the set becoming more discriminable from each other, thensets within other regions of the color space must be compressed, withtheir colors becoming less discriminable from each other. Thisphenomenon is exploited in the color test described herein to estimatethe calibration state of the display: by testing color discriminationwithin several regions of the color space (e.g., bluish, greenish,reddish, and around the white point), we can determine if discriminationperformance differs across regions as compared to performance by a“normal” observer tested on a fully calibrated monitor.

Luminance output does not increase linearly with voltage applied to aCRT gun, and the nonlinearity is well characterized by a power function,where gamma is an exponent in the range of 2.2 to 2.6. In addition, aluminance pedestal may remain at what is nominally zero voltage. Thesenonlinearities are commonly corrected by applying the inverse transformthrough a lookup table. However, using a single, average transform tocorrect for an average error across all displays means that individualerrors will remain for most displays. For optimal correction, theindividual monitor must be calibrated. However, since this is best doneby using a photometer or similar instrument, it is unlikely that theaverage computer user will be able to do this.

FIGS. 1 a and 1 b collectively illustrate the pattern of chromaticshifts for various values of gamma. FIG. 1 a illustrates the pattern ofchromatic shift for gamma=1.2 (undercorrected). FIG. 1 b, on the otherhand, illustrates the pattern of chromatic shift for gamma=0.8(overcorrected).

Errors in gamma correction lead to systematic shifts in the displayedcolors across the monitor's gamut. For undercorrection, colors shiftaway from the white point and towards the primary chromaticities, asindicated FIG. 1 a. There are three lines (not drawn), emanating fromeach of the primary chromaticities and passing through the white point,that act as chromatic watersheds-colors on either side of such a lineare displaced away from it in the case of undercorrected gamma, or areattracted towards it if gamma is overcorrected. Thus, two colors oneither side of such a line will be further apart than their nominalvalues if gamma is undercorrected and will therefore be more easilydiscriminable, which is a highly undesirable trait in a color test. Itshould be noted that colors converge near the vertices of the trianglein the case of undercorrected gamma; this property is exploited in thedisclosed color test. For gamma overcorrection (FIG. 1 b), the patternof chromatic shifts is reversed.

Monitors have controls to set the color balance. Factory settings maynot correspond to a standard white point, and users may well manipulatethem. A color deficient observer may choose extreme settings, whichcould strongly bias test results either to facilitate diagnosis or tomisdirect it. FIG. 2 shows an example of a red shift. Note that thepattern of chromatic shifts is systematic, with regions of divergenceand convergence. This pattern can be used to identify color shifts sincecolors in one part of the space will be more easily discriminable thanin other parts.

The present invention provides for a method and a system that overcomessuch calibration problems in display devices by testing colordiscrimination within several regions of a color space and determiningif a test subject has any of the above-mentioned color deficiencies(protanopia, deuteranopia, and tritanopia).

FIG. 3 a illustrates a selection of colors within a color space.Triangle 301 shows the range of colors obtainable on a CRT monitor asplotted on a CIE diagram (a standard rendering of color space), shown asa horseshoe-shaped thick curve 304. Additionally, in the example, one ofthe confusion lines 302 for a deuteranope is shown. The target color 306(large white dot, outlined with a black border) is chosen to lie on theconfusion line. A distractor set of colors (shown as an array of dots308) is chosen so that it extends above and below the luminance planeshared with the target, and is placed so the confusion line passingthrough the target color also passes approximately through the middle ofthe set.

FIG. 3 b shows a close-up, top-down view of the equiluminant plane shownin FIG. 3 a. The confusion line passing through the target color (largecircle) intersects roughly the centroid of the distractor color set(shown as a row of dots). This distractor set is approximately alignedwith the plane normal to the confusion line.

Greater separation between the target color and the distractor set makesidentification of the target easier, while smaller separations makeidentification more difficult.

FIG. 4 illustrates an example showing the appearance of a test plate.Distractor colors are quasi-randomly assigned to different patches in avisual display. The target color is assigned to a patch at aquasi-randomly selected location of the display on each trial. An actualtest plate rendered on a subject's display device is in color, with onesquare in the test plate representing the target color. Since theluminance of the target element lies within the luminance distributionof the distractor set, the target is distinguishable from the distractorset only by chromaticity.

The present invention is implemented, in one embodiment, using asoftware engine, based on standard methods, which chooses the stimulusparameters to be tested on any given trial and initiates the next trial.The stimulus sequence engine also keeps track of completed trials andall conditions, and it stores all the data. The test is completed whenthresholds have been measured for all conditions.

The test can be administered as a fixed number of conditions that arepresented to each observer. The conditions are described in sections A,B, and C below. In this case, the total number of trials equals thenumber of conditions in A times the number of conditions in B times thenumber of conditions in C.

A: Different Types of Color Vision Deficiencies

At least three separate test sequences are necessary to determine if anobserver exhibits any of the three major categories of color visiondeficiency or their subcategories.

B: Testing within Several Regions of Color Space

Each test sequence in A must be repeated in several regions of colorspace (3 or 4 regions are probably sufficient). FIGS. 5 a-c collectivelyillustrate testing within several regions of the color space. FIG. 5 aillustrates a specific instance wherein the test sequence is performedin the region corresponding to the green color. FIG. 5 b, on the otherhand, corresponds to a test sequence that is repeated in the regioncorresponding to the red color. Lastly, FIG. 5 c illustrates the testsequence as repeated around the region corresponding to the white point(not shown).

C: Trials to Measure Threshold to Identify the Target within DistractorSet

The chromaticity of the target color differs from the average (orcentroid) of the chromaticities of the colors in the distractor set. Theseparation between the target color and the distractor centroid isvaried in the color test to measure the observer's ability to identifythe target color within the distractor set. This can be done with anynumber of standard threshold measurement methods. For example, thestaircase method adaptively increases the value of the color separationas long as an observer is not able to consistently identify the targetcolor, and decreases the separation again until the observer is nolonger able to consistently identify the target. This is repeated anumber of times, and the average of the upper and lower staircasereversal points is used as an estimate of the detection threshold.

The color test can be implemented using a fixed number of staircasereversals. After completion, the variance of the reversal points iscalculated, and the value of the average, representing the threshold, isaccepted if the variance is below a chosen value. Otherwise, the test isdeemed inconclusive, and the observer can be asked to seek furthertesting, or the test may be repeated with an equal or larger number ofreversals.

A user's thresholds are compared to a database of average thresholds fora population of color normal observers tested on fully calibratedmonitors. A user passes a particular subtest if the thresholds are lessthan or equal to the corresponding thresholds for the normal comparisonpopulation, or if they are no greater than a statistical criterion valuebased on the variance of the measurements. An observer is deemed to havefunctional color vision if he or she passes all subtests within themaster color test battery. Otherwise, the user is urged to seek furthertesting.

FIG. 6 illustrates an exemplary embodiment associated with the method600 of the present invention for testing in a plurality of regions in acolor space to identify any of, or a subcombination of, or anomaliesrelated to, the following color vision deficiencies: protanopia,deuteranopia, and tritanopia. The method comprises the following steps:

Step 602: A test plate is displayed in this step, wherein the test platemade up of a target color and an array of distractor set of colors, andthe target color selected to lie on a confusion line associated with anyof said color vision deficiencies. The target and distractor colors arere-assigned to random locations on each trial.

Step 604: A subject's ability to accurately identify the target color inthe test plate is identified.

Step 606: Vary, adaptively, the chromatic separation between the targetcolor and a centroid (said centroid representing an average ofchromaticities of colors associated with said distractor set) of thedistractor set of colors to help identify a threshold that defines thesubject's ability to identify the target color;

Step 608: Repeat steps 602 through 606 in a plurality of regions in saidcolor space and identifying a set of thresholds.

Step 610: Compare the identified set of thresholds against a database ofaverage thresholds corresponding to subjects tested on calibrateddisplay device.

Step 612: If the identified thresholds are greater than correspondingthresholds in the database, then indicate to the subject the presence ofcolor deficiency corresponding to the target color (depending on whichconfusion line the target color is on).

It should be noted that the steps of the above-described method arerepeated with a different test plate to identify the presence/absence ofany of the three color deficiencies (or their sub-combinations orvariants).

FIG. 7 illustrates a method 700 outlining an exemplary application ofthe present invention, wherein the method 700 includes the steps of: (a)logging in to a website (step 702); (b) starting a color test (step704); (c) reading instructions (step 706) such as: “Click on the elementin the mosaic whose color is most different from the other elements inthe group”; (d) viewing a demo trial (step 708) with an obvious target(colors chosen so that they do not lie on any of the major confusionlines and the target is of greatly different luminance from all theelements in the distractor set); (e) clicking on the target (step 710);(f) receiving feedback (step 712) (e.g., a light-enhanced outline, atone signal, or a spoken or written “ok” vs. “incorrect” message); (g)starting vision test and repeating this sequence for a series of imagesand, after a number of trials (step 714), and (h) receiving the result(step 716): “Color vision ok.” or “Please seek further testing”.

FIG. 8 illustrates a system implementing the present invention's visiontesting method via a stand-alone vision testing server 802 or a visiontesting server working in conjunction with an Internet Service Provider(ISP) 804. On the client's (subject's) side, equipment to implement themethod of the present invention include, but are not limited to: acomputer 806, a display device 807 such as a cathode ray tube (CRT)display monitor, an input device 808 such as a mouse and/or keyboard,and a communication link for accessing data related to the vision testover a network 810, 812. Thus, in one embodiment, the user is able todirectly access vision testing server 802 over network 812. In anotherembodiment, the user is able to access vision testing server 802 via ISP804 (which in turn is able to access the vision testing server overnetwork 814). The network cloud (810, 812, 814) shown in FIG. 8 could beany of, or a combination of, the following (but not limited to)networks: local area networks (LANs), wide area networks (WANs), or theInternet. Thus, the vision test can be administered over a network suchas the World Wide Web as long as the subject has access to such anetwork and a web browser to run the test. Additionally, the method canbe implemented using a variety of Internet access protocols. On the hostside, a software module controls the sequence of test presentations,data collection, and test evaluation.

Furthermore, the present invention includes computer program code, whichis stored on a storage medium and which can be used to instruct acomputer to perform any of the methods associated with the presentinvention. The computer storage medium includes any of, but is notlimited to, the following: CD-ROM, DVD, magnetic tape, optical disc,hard drive, floppy disk, ferroelectric memory, flash memory,ferromagnetic memory, optical storage, charge coupled devices, magneticor optical cards, smart cards, EEPROM, EPROM, RAM, ROM, DRAM, SRAM,SDRAM, and/or any other appropriate static or dynamic memory or datastorage device.

Implemented in the computer readable program code are software modulesfor computer readable program code for: (a) displaying a test plate,said test plate made up of a target color and an array of distractor setof colors, said target color selected to lie on a confusion lineassociated with any of said color vision deficiencies; (b) identifying asubject's ability to accurately identify said target color in said testplate; (c) adaptively varying chromatic separation between said targetcolor and a centroid of said distractor set of colors to identify athreshold that identifies said subject's ability to identify said targetcolor, said centroid representing an average of chromaticities of colorsassociated with said distractor set; (d) repeating steps a-c in aplurality of regions in said color space and identifying a set ofthresholds; (e) comparing said identified set of thresholds against adatabase of average thresholds corresponding to subjects tested on acalibrated display device and, if said identified threshold is less thana corresponding threshold in said database, indicating to said subjectan absence of color deficiency corresponding to said target color; and(f) repeating steps a-e with a different test plate to identify any ofsaid color deficiencies.

Although the present invention has been shown and described with respectto several preferred embodiments thereof, various changes, omissions,and additions to the form and detail thereof may be made therein withoutdeparting from the spirit and scope of the invention.

1. A color deficiency vision test implemented on a computer and a mediumcapable of rendering a range of colors defined by a color space, saidcomputer being associated with a test subject, said test comprising thesteps of: a. selecting a confusion line associated with a particularcolor vision deficiency; b. selecting a set of distractor colorsextending in luminance, or chromaticity, or both luminance andchromaticity, said distractor set oriented so it is approximatelyaligned with the plane normal to said confusion line and intersectedapproximately at its centroid or within its convex hull by saidconfusion line, extending above, or below, or above and below, or lyingon, the luminance plane on which said confusion line is located; c.selecting a target color in said color space, said target colorseparated from said distractor set by a chromatic separation along saidconfusion line associated with a particular color vision deficiency; d.quasi-randomly assigning the distractor and target colors to locationsin a test plate; e. rendering a plurality of modified test plates totest for color vision deficiency corresponding to said target color,said modification based upon varying the distance between saiddistractor set and said target color; and f. repeating steps c-d inmultiple regions of said color space and identifying the presence orabsence of said particular color vision deficiency.
 2. A colordeficiency vision test implemented on a computer and a medium capable ofrendering a range of colors defined by a color space, said computerbeing associated with a test subject, as per claim 1, wherein saididentification for the presence or absence of said particular colorvision deficiency is based upon a threshold associated with saidvariance in the distance between said distractor set and said targetcolor.
 3. A color deficiency vision test implemented on a computer and amedium capable of rendering a range of colors defined by a color space,said computer being associated with a test subject, as per claim 2,wherein said threshold is identified via an adaptive method, saidadaptive method comprising the steps of: a. adaptively increasing saiddistance between said distractor set and said target color to identify aset of upper range points where said test subject is able to identifysaid target color; b. adaptively decreasing distance between saiddistractor set and said target color to identify a set of lower rangepoints where said test subject is unable to identify said target color;and c. identifying said threshold based upon an average of said upperrange points and lower range points.
 4. A color deficiency vision testimplemented on a computer and a medium capable of rendering a range ofcolors defined by a color space, as per claim 1, wherein said colordeficiencies are any of, a sub-combination of, or related anomalies ofthe following: protanopia, deuteranopia, or tritanopia.
 5. A colordeficiency vision test implemented over a network and rendered on amedium capable of displaying a range of colors defined by a color space,said network-based color deficiency test comprising the steps of: a.receiving a request for a network-based color deficiency vision testfrom a test subject over said network;  transmitting instructions oversaid network to a computing device associated with said test subject andsaid medium, said instructions: i. identifying a target color, saidtarget color selected to lie on or near a confusion line associated witha particular color vision deficiency; ii. identifying or creating a testplate comprising said target color and an array of distractor colors,said distractor set extending above, or below, or above and below, orlying on,a luminance plane shared with said target color in said colorspace, said target color separated from the color set in said array by achromatic separation; iii. aiding said medium in rendering a pluralityof modified test plates, said modified test plates testing for colorvision deficiency corresponding to said target color, said modificationbased upon varying the distance between said distractor set and saidtarget color; and b. transmitting instructions for repeating steps c-din multiple regions of said color space and identifying the presence orabsence of said particular color vision deficiency.
 6. A colordeficiency vision test implemented over a network and rendered on amedium capable of displaying a range of colors defined by a color space,as per claim 5, wherein said color deficiencies are any of, asub-combination of, or related anomalies of the following: protanopia,deuteranopia, or tritanopia.
 7. A color deficiency vision testimplemented over a network and rendered on a medium capable ofdisplaying a range of colors defined by a color space, as per claim 5,wherein said identification of the presence or absence of saidparticular vision deficiency is based upon a threshold associated withsaid variance in the distance between said distractor set and saidtarget color.
 8. A color deficiency vision test implemented over anetwork and rendered on a medium capable of displaying a range of colorsdefined by a color space, as per claim 7, wherein said threshold isidentified via an adaptive method, said adaptive method comprising thesteps of: a. adaptively increasing said distance between said distractorset and said target color to identify a set of upper range points wheresaid test subject is able to identify said target color; b. adaptivelydecreasing distance between said distractor set and said target color toidentify a set of lower range points where said test subject is unableto identify said target color; and c. identifying said threshold basedupon an average of said upper range points and lower range points.
 9. Amethod for testing and identifying color vision deficiencies associatedwith a test subject, said method comprising the steps of: a. displayinga test plate in a medium capable of rendering a range of colors definedby a color space, said test plate comprising a target color and an arrayof distractor colors, said distractor set extending above, or below, orabove and below, or lying on,a luminance plane shared with said targetcolor in said color space, said target color selected to lie on aconfusion line associated with a particular color vision deficiency,said target color separated from said distractor set by a chromaticseparation; b. adaptively varying said chromatic separation between saidtarget color and the centroid of said distractor set of colors aplurality of times to identify an average threshold that identifies saidtest subject's ability to identify said target color in said test plate,said centroid representing an average of said distractor set's colorcoordinates in said color space; and c. comparing said identifiedaverage threshold against a database of average thresholds correspondingto subjects tested on a standardized display medium and, if saididentified average threshold is greater than corresponding averagethreshold in said database, indicating to said test subject the presenceof said particular color deficiency corresponding to said target color.10. A method for testing and identifying color vision deficienciesassociated with a test subject, as per claim 9, wherein steps a-c arerepeated using a plurality of target colors lying in different confusionlines to identify the presence of other color vision deficiencies.
 11. Amethod for testing and identifying color vision deficiencies associatedwith a test subject, as per claim 9, wherein said average threshold isidentified via an adaptive method, said adaptive method comprising thesteps of: a. adaptively increasing said chromatic separation to identifya set of upper range points where said subject is able to identify saidtarget color; b. adaptively decreasing said chromatic separation toidentify a set of lower range points where said subject is unable toidentify said target color; and c. identifying said average thresholdbased upon an average of said upper range points and lower range points.12. A method for testing and identifying color vision deficienciesassociated with a test subject, as per claim 9, wherein said colordeficiencies are any of, a sub-combination of, or related anomalies ofthe following: protanopia, deuteranopia, or tritanopia.
 13. An articleof manufacture comprising a computer usable medium having computerreadable program code embodied therein for testing and identifying colorvision deficiencies associated with a test subject, said mediumcomprising: a. computer readable program code aiding in displaying atest plate in a medium capable of rendering a range of colors defined bya color space, said test plate comprising a target color and an array ofdistractor colors, said distractor set extending above, or below, orabove and below, or lying on, a luminance plane shared with said targetcolor in said color space, said target color selected to lie on aconfusion line associated with a particular color vision deficiency,said target color separated from said distractor set by a chromaticseparation; b. computer readable program code adaptively varying saidchromatic separation between said target color and a centroid of saiddistractor set of colors a plurality of times to identify an averagethreshold that identifies said test subject's ability to identify saidtarget color in said test plate, said centroid representing an averageof said distractor set's color coordinates in said color space; and c.computer readable program code comparing said identified averagethreshold against a database of average thresholds corresponding tosubjects tested on a standardized display medium and, if said identifiedaverage threshold is greater than corresponding average threshold insaid database, indicating to said test subject the presence of saidparticular color deficiency corresponding to said target color.
 14. Anarticle of manufacture comprising a computer usable medium havingcomputer readable program code embodied therein for testing andidentifying color vision deficiencies associated with a test subject, asper claim 13, wherein said average threshold is identified via anadaptive method, said adaptive method as implemented in computerreadable program code comprising the steps of: a. adaptively increasingsaid chromatic separation to identify a set of upper range points wheresaid subject is able to identify said target color; b. adaptivelydecreasing said chromatic separation to identify a set of lower rangepoints where said subject is unable to identify said target color; andc. identifying said average threshold based upon an average of saidupper range points and lower range points.
 15. A method for testing atest subject for one or more color vision deficiencies via a mediumcapable of rendering a range of colors defined by a color space, saidmethod implemented over a network, said method comprising the steps of:a. receiving a request for testing one or more color deficiencies oversaid network; b. transmitting data over said network for rendering atest plate in said medium, said test plate comprising a target color andan array of distractor colors, said distractor set extending above, orbelow, or above and below, or lying on, a luminance plane shared withsaid target color in said color space, said target color selected to lieon a confusion line associated with a particular color visiondeficiency, said target color separated from said distractor set by achromatic separation; c. transmitting instructions over said network foradaptively varying said chromatic separation between said target colorand a centroid of said distractor set of colors a plurality of times toidentify an average threshold that identifies said test subject'sability to identify said target color in said test plate, said centroidrepresenting an average of said distractor set's color coordinates insaid color space; d. receiving said identified average threshold; e.accessing a database and comparing said identified average thresholdagainst a corresponding average threshold value in said database, saidaverage threshold values in said database corresponding to subjectstested on a standardized display medium; and f. if said identifiedaverage threshold is greater than corresponding average threshold insaid database, transmitting an indicator to said test subject indicatingthe presence of said particular color deficiency corresponding to saidtarget color.
 16. A method for testing a test subject for one or morecolor vision deficiencies via a medium capable of rendering a range ofcolors defined by a color space, said method implemented over a network,as per claim 15, wherein said color deficiencies are any of, asub-combination of, or related anomalies of the following: protanopia,deuteranopia, or tritanopia.
 17. A method for testing and identifyingcolor vision deficiencies associated with a test subject, said methodcomprising the steps of: a. displaying a test plate in a medium capableof rendering a range of colors defined by a color space, said test platecomprising a target color and an array of distractor colors, saiddistractor set extending above, or below, or above and below, or lyingon,a luminance plane shared with said target color in said color space,said target color selected to lie on a confusion line associated with aparticular color vision deficiency, said target color separated fromsaid distractor set by a chromatic separation representative ofthresholds in a database of average thresholds corresponding to subjectstested on a standardized display medium; b. determining said testsubject's ability to identify said target color in said test plate, saidcentroid representing an average of said distractor set's colorcoordinates in said color space; and c. indicating to said test subjectthe presence of said particular color deficiency corresponding to saidtarget color if said subject is unable to identify said target color.